To a Sick Man
Gilāna Sutta  (AN 5:121)

I have heard that on one occasion the Blessed One was staying near Vesālī in the Gabled Hall at the Great Forest. Then, on emerging from his seclusion in the late afternoon, he went to the sick ward, where he saw a monk who was weak & sickly. Seeing him, he sat down on a prepared seat. Having sat down there, he addressed the monks: “When these five things don’t leave a monk who is weak & sickly, it can be expected of him that, before long—with the ending of the effluents—he will enter & remain in the effluent-free awareness-release & discernment-release, having directly known & realized them for himself right in the here & now. Which five?

“There is the case where a monk [1] remains focused on unattractiveness with regard to the body, [2] is percipient of loathsomeness in food, [3] is percipient of distaste with regard to every world, [4] remains focused on inconstancy with regard to all fabrications. [5] The perception of death is well established within him.

“When these five things don’t leave a monk who is weak & sickly, it can be expected of him that, before long—with the ending of the effluents—he will enter & remain in the effluent-free awareness-release & discernment-release, having directly known & realized them for himself right in the here & now.”

See also: SN 36:7; SN 46:14; AN 7:46; AN 10:60